Developmental origins of health and disease (DOHaD) is the study of how the early life environment can impact the risk of chronic diseases from childhood to adulthood and the mechanisms involved. Epigenetic modifications such as DNA methylation, histone modifications and non-coding RNAs are involved in mediating how early life environment impacts later health. This review is a summary of the Epigenetics and DOHaD workshop held at the 2016 DOHaD Society of Australia and New Zealand Conference. Our extensive knowledge of how the early life environment impacts later risk for chronic disease would not have been possible without animal models. In this review we highlight some animal model examples that demonstrate how an adverse early life exposure results in epigenetic and gene expression changes that may contribute to increased risk of chronic disease later in life. Type 2 diabetes and cardiovascular disease are chronic diseases with an increasing incidence due to the increased number of children and adults that are obese. Epigenetic changes such as DNA methylation have been shown to be associated with metabolic health measures and potentially predict future metabolic health status. Although more difficult to elucidate in humans, recent studies suggest that DNA methylation may be one of the epigenetic mechanisms that mediates the effects of early life exposures on later life risk of obesity and obesity related diseases. Finally, we discuss the role of the microbiome and how it is a new player in developmental programming and mediating early life exposures on later risk of chronic disease.

Intrauterine growth restriction (IUGR) followed by accelerated growth after birth is associated with an increased risk of abdominal (visceral) obesity and insulin resistance in adult life. The aim of the present study was to determine the impact of IUGR on mRNA expression and protein abundance of insulin signaling molecules in one of the major visceral fat depots, the omental adipose depot. IUGR was induced by placental restriction, and samples of omental adipose tissue were collected from IUGR (n = 9, 5 males, 4 females) and Control (n = 14, 8 males, 6 females) neonatal lambs at 21 days of age. The mRNA expression of the insulin signaling molecules, AMP-kinase (AMPK) and adipogenic/lipogenic genes was determined by qRT-PCR, and protein abundance by Western Blotting. AMPKα2 mRNA expression was increased in male IUGR lambs (0.015 ± 0.002 v. 0.0075 ± 0.0009, P < 0.001). The proportion of the AMPK pool that was phosphorylated (%P-AMPK) was lower in IUGR lambs compared with Controls independent of sex (39 ± 9% v. 100 ± 18%, P < 0.001). The mRNA expression and protein abundance of insulin signaling proteins and adipogenic/lipogenic genes was not different between groups. Thus, IUGR is associated with sex-specific alterations in the mRNA expression of AMPKα2 and a reduction in the percentage of the total AMPK pool that is phosphorylated in the omental adipose tissue of neonatal lambs, before the onset of visceral obesity. These molecular changes would be expected to promote lipid accumulation in the omental adipose depot and may therefore contribute to the onset of visceral adiposity in IUGR animals later in life.

It is widely recognized that environmental insults during adulthood including smoking, lack of exercise and a poor diet increases an individual's risk of cardiovascular disease (CVD). However, research initiated over the last two decades has highlighted that our risk of CVD can be programmed following adverse exposures during early development. Such adverse exposures may include, undernutrition, placental insufficiency, hypoxia, overnutrition and obesity. This review aims to address the current Western obesity crisis by addressing the long-term impact of maternal overnutrition and obesity on the offspring's future risk of CVD. Although current human studies have observed the presence of adverse CVD markers in children born to obese mothers, animal models have proved vital in understanding the underlying mechanisms involved. Mechanisms suggested to be involved in the programming of CVD in the offspring include increased oxidative stress, inflammation, lipotoxicity and epigenetics. CVD remains the greatest cause of death worldwide, therefore further understanding of the mechanisms mediating these effects is important in the development of intervention strategies.

Individuals exposed in utero to maternal obesity have increased risk of developing type 2 diabetes mellitus and obesity in adulthood. The molecular mechanisms underlying this association are unknown. We have therefore used a murine model of maternal obesity, in which the offspring of obese dams develop hyperinsulinaemia by 3 months of age indicative of insulin resistance. Here, we investigate the effects of maternal diet-induced obesity on the expression/phosphorylation of key hepatic insulin signalling proteins and the expression of anti-oxidant enzymes in male offspring. At 3 months of age, offspring of obese dams had decreased levels of insulin receptor substrate (IRS) 1 (P < 0.01), whereas the ratio of phosphorylated IRS1 Ser307 to total IRS1 was significantly increased (P < 0.001), suggesting that it was less active. Protein expression of the PI3K p85α subunit was decreased (P < 0.01) and there was a tendency for phosphorylation of Akt at Ser473 to be reduced (P = 0.08) in the offspring of obese dams. protein kinase Cζ (P < 0.001) and glycogen synthase kinase 3β (P < 0.05) levels were increased in these animals in comparison with controls. Maternal obesity also resulted in increased phosphorylation of p38 mitogen-activated protein kinase at Thr180/Tyr182 (P < 0.01) and raised c-Jun N-terminal kinase 1 expression (P < 0.5) in the offspring. The expression of antioxidant enzymes was also affected by maternal obesity with CuZnSOD (P < 0.001) and glutathione reductase (P < 0.05) being increased, whereas glutathione peroxidase 1 was reduced (P < 0.05) in the offspring. We conclude that maternal obesity leads to alterations in hepatic insulin signalling protein expression and phosphorylation. These molecular changes may contribute to the development of insulin resistance.

Many adult diseases, including type 2 diabetes, hypertension and cardiovascular disease, are related to low birth weight. The mechanistic basis of this relationship is not known. To investigate the role of fetal undernutrition, we used a rat model of maternal protein restriction in which dams were fed a diet containing 80 g protein/kg (v. 200 g/kg in the control group) throughout gestation and lactation. Offspring were born smaller than controls and in adulthood developed diabetes, hyperinsulinaemia and tissue insulin resistance. To determine possible mechanisms of fetal programming, circulating levels of several hormones were measured in maternal plasma at gestational days 14, 17 and 21 and fetal plasma at gestational day 21. Several differences were noted at day 14, when glucose concentrations in maternal and feto–placental blood were raised significantly (P=0·04 and P=0·0001 respectively); insulin levels in the low-protein (LP) dams were raised (P=0·04), prolactin levels were raised (P=0·047) and progesterone levels were reduced (P=0·02). Circulating 17β-oestradiol in the LP dams was raised by 35% over those of the controls from day 17 to day 21 (P=0·008). A significant decrease in maternal leptin levels (P=0·004) was observed at gestation on day 21. Neither oestradiol nor leptin levels were altered in the fetal circulation at day 21. Maternal and fetal corticosterone levels were comparable with control levels, suggesting that they do not initiate the programming effects in this model. Our present results suggest that maternal protein restriction imposes changes in maternal levels of glucose, insulin, prolactin, progesterone, oestradiol and leptin; these changes could influence the programming of eventual adult disease in the developing fetus.

In rats, maternal anaemia during pregnancy causes hypertension in the adult offspring, although the mechanism is unknown. The present study investigated the renal morphology of adult rats born to mothers who were Fe-deficient during pregnancy. Rats were fed either a control (153 mg Fe/kg diet, n 7) or low-Fe (3 mg/kg diet, n 6) diet from 1 week before mating and throughout gestation. At delivery, the Fe-restricted (IR) mothers were anaemic; the IR pups were also anaemic and growth-retarded at 2 d of age. At 3 and 16 months, systolic blood pressure in the IR offspring (163 (sem 4) and 151 (sem 4) mmHg respectively, n 13) was greater than in control animals (145 (sem 3) and 119 (sem 4) mmHg respectively, n 15, P<0·05). At post mortem at 18 months, there was no difference in kidney weight between treatment groups, although relative kidney weight as a fraction of body weight in the IR offspring was greater than in control animals (P<0·05). Glomerular number was lower in the IR offspring (11·4 (sem 1·1) per 4mm2, n 13) compared with control rats (14·8 (sem 0·7), n 15, P<0·05). Maternal treatment had no effect on glomerular size, but overall, female rats had smaller and more numerous glomeruli per unit area than male rats. When all animals were considered, inverse relationships were observed between glomerular number and glomerular size (r−0·73, n 28, P<0·05), and glomerular number and systolic blood pressure at both 3 months (r−0·42, n 28, P<0·05) and 16 months of age (r−0·64, n 28, P<0·05). Therefore, in rats, maternal Fe restriction causes hypertension in the adult offspring that may be due, in part, to a deficit in nephron number.